Dual feed liquid drop ejector

ABSTRACT

A liquid ejector includes a structure defining a chamber. The chamber includes a first surface and a second surface. The first surface includes a nozzle orifice. A drop forming mechanism is located on the second surface of the chamber opposite the nozzle orifice. A first liquid feed channel and a second liquid feed channel are in fluid communication with the chamber. A first segment of a segmented liquid inlet is in fluid communication with the first liquid feed channel and a second segment of the segmented liquid inlet is in fluid communication with the second liquid feed channel.

FIELD OF THE INVENTION

This invention relates generally to the field of digitally controlledprinting systems, and in particular to the liquid drop ejector componentof these systems.

BACKGROUND OF THE INVENTION

In the field of inkjet printing, there is a desire to provide betterquality prints more quickly than can be provided using commerciallyavailable printheads. Accordingly, efforts have been made to increaseinkjet printhead operating frequencies and improve the placementaccuracy of drops ejected from inkjet printheads, see, for example, U.S.patent application Publication No. U.S. 2004/0263578 A1, published onDec. 30, 2004.

U.S. patent application Publication No. U.S. 2004/0263578 A1 disclosesan inkjet printhead that includes a substrate having an ink chamber anda manifold, a nozzle plate formed on the substrate, first and secondheaters, first and second conductors, and first and second ink channels.The nozzle plate includes a nozzle passing through the nozzle plate andin flow communication with the ink chamber. The first and second heatersand conductors are interposed between adjacent passivation layers of thenozzle plate. The ink channels are interposed between the ink chamberand the manifold, for providing flow communication between the inkchamber and the manifold. The first and second heaters, conductors andink channels are symmetric with respect to the nozzle.

Notwithstanding these efforts, there is still a need for liquid dropejectors that have increased firing frequency and increased accuracy fordrop ejection and drop placement on a receiver.

SUMMARY OF THE INVENTION

According to one feature of the present invention, a liquid ejectorincludes a structure defining a chamber. The chamber includes a firstsurface and a second surface. The first surface includes a nozzleorifice. A drop forming mechanism is located on the second surface ofthe chamber opposite the nozzle orifice. A first liquid feed channel anda second liquid feed channel are in fluid communication with thechamber. A first segment of a segmented liquid inlet is in fluidcommunication with the first liquid feed channel and a second segment ofthe segmented liquid inlet is in fluid communication with the secondliquid feed channel.

According to another feature of the present invention, a liquid ejectorincludes a structure defining an array of chambers with each chamberhaving a nozzle orifice. A drop forming mechanism is located in eachchamber. First and second liquid feed channels are in fluidcommunication with each chamber. The first and second feed channelsextend in opposite directions from each chamber. A segmented inletincludes a plurality of first segments and a plurality of secondsegments. Each of the first segments of the liquid inlet is in fluidcommunication with the first liquid feed channels and each of the secondsegments of the liquid inlet is in fluid communication with the secondliquid feed channels. The plurality of first segments and the pluralityof second segments are located on opposite sides of the nozzle orifice.

According to another feature of the present invention, a liquid ejectorincludes a structure defining a chamber having a nozzle orifice. A dropforming mechanism is located in the chamber. First and second liquidfeed channels are in fluid communication with the chamber. A firstsegment of a segmented liquid inlet is in fluid communication with thefirst liquid feed channel. A second segment of the segmented liquidinlet is in fluid communication with the second liquid feed channel. Thefirst segment of the liquid inlet and the second segment of the liquidinlet are positioned offset relative to each other as viewed from aplane perpendicular to the nozzle orifice.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description of the preferred embodiments of theinvention presented below, reference is made to the accompanyingdrawings, in which:

FIG. 1 is a schematic representation of a liquid ejection systemincorporating the present invention;

FIGS. 2 a and 2 b are schematic top views of a liquid ejection printheaddie incorporating an example embodiment of the present invention inwhich ends of adjacent inlet segments are aligned;

FIG. 3 is a schematic top view of a liquid ejection printhead dieincorporating an example embodiment of the present invention in whichends of adjacent inlet segments overlap;

FIG. 4 is a schematic top view of a liquid ejection printhead dieincorporating an example embodiment of the present invention in whichends of adjacent inlet segments are spaced apart;

FIG. 5 is a schematic cross sectional view of one liquid ejector shownthrough line 5-5 of FIG. 4;

FIG. 6 is a schematic top view of a liquid ejection printhead dieincorporating an example embodiment of the present invention in whichthe posts are asymmetrically positioned within the feed channels;

FIG. 7 is a schematic top view of a liquid ejection printhead dieincorporating an example embodiment of the present invention in whichthe posts have different cross-sectional areas;

FIG. 8 is a lower magnification of a portion of a liquid ejectionprinthead die incorporating an example embodiment of the presentinvention in which additional posts are disposed between the inletsegments and the feed channels;

FIG. 9 is a schematic top view of a liquid ejection printhead dieincorporating an example embodiment of the present invention in whichnone of the electrical leads extend toward a plurality of inletsegments;

FIG. 10 is a schematic top view of a liquid ejection printhead dieincorporating another example embodiment of the present invention inwhich none of the electrical leads extend toward a plurality of inletsegments;

FIG. 11 is a schematic top view of a liquid ejection printhead dieincorporating an example embodiment of the present invention in whichpower circuitry and logic circuitry are integrated on the printhead die;

FIG. 12 is a schematic top view of a liquid ejection printhead dieincorporating another example embodiment of the present invention inwhich power circuitry and logic circuitry are integrated on theprinthead die;

FIG. 13 is a schematic top view of a liquid ejection printhead dieincorporating an example embodiment of the present invention includingtwo staggered rows of liquid ejectors;

FIG. 14 is a schematic top view of a liquid ejection printhead dieincorporating an example embodiment of the present invention includingtwo aligned rows of liquid ejectors;

FIGS. 15-17 are schematic top views of liquid ejection printhead dieincorporating example embodiments of the present invention in which theratio of the number of liquid ejectors to the number of inlet segmentsis less than two; and

FIG. 18 is a schematic top view of a liquid ejection printhead dieincorporating an example embodiment of the present invention includingtwo staggered rows of liquid ejectors where the nozzle cross-sectionalarea is different in the two rows.

DETAILED DESCRIPTION OF THE INVENTION

The present description will be directed in particular to elementsforming part of, or cooperating more directly with, apparatus inaccordance with the present invention. It is to be understood thatelements not specifically shown or described may take various forms wellknown to those skilled in the art. In the following description,identical reference numerals have been used, where possible, todesignate identical elements.

Although the term liquid ejection printhead is used herein, it isrecognized that printheads are being used today to eject many types ofliquids and not just ink. For example, the ejection of various liquidsincluding medicines, pigments, dyes, conductive and semi-conductiveorganics, metal particles, and other materials is possible today using aliquid ejection printhead. As such, the term printhead is not intendedto be limited to just devices that eject ink.

One aspect of the invention described herein relates to theconfiguration of the liquid ejector and, in particular, the relationshipof a drop forming mechanism and its corresponding liquid feed channels.Particular embodiments are described relating to thermal inkjetprintheads in which the drop forming mechanism is a resistive heatingelement that is pulsed to nucleate a bubble in an ink-filled chamber,and eject a droplet as the bubble expands. Other embodiments includepiezoelectric printheads, as well as MEMS type printheads, e.g. those inwhich the drop forming mechanism is a thermal bend actuator or anelectrostatic actuator. Preferred fabrication methods include thosedescribed in copending applications U.S. Ser. No. 11/609,375, filed Dec.12, 2006, entitled “LIQUID DROP EJECTOR HAVING IMPROVED LIQUID CHAMBER”in the name of John A. Lebens and U.S. Ser. No. 11/609,365, filed Dec.12, 2006, entitled “LIQUID EJECTOR HAVING IMPROVED CHAMBER WALLS” in thename of John A. Lebens et al. These applications describe methods forforming chambers and nozzle plates in an integrated fashion with thedrop forming mechanism. However, this invention may also be practicedusing more conventional fabrication methods, such as forming the nozzleplate as a separate component from the substrate on which the resistiveheating elements are formed and then bonding the two componentstogether.

Referring to FIG. 1, a schematic representation of a liquid ejectionsystem 10, for example, an inkjet printer, is shown. Liquid ejectionsystem 10 includes a source 12 of data (for example, image data) whichprovides signals that are interpreted by a controller 14 as beingcommands to eject liquid drops. Controller 14 outputs signals to asource 16 of electrical energy pulses which are sent to a liquidejection printhead die 18. Typically, liquid ejection printhead die 18includes a plurality of liquid ejectors 20 arranged in at least onearray, for example, a substantially linear row. During operation,liquid, for example, ink in the form of ink drops, is deposited on arecording medium 24.

Referring additionally to FIGS. 2 a and 2 b, a schematic representationsof a liquid ejection printhead die 18 are shown. Liquid ejectionprinthead die 18 includes an array or plurality of liquid ejectors 20.Liquid ejector 20 includes a structure, for example, walls 26 extendingfrom a substrate 28 that define a chamber 30. Walls 26 separate liquidejectors 20 positioned adjacent to other liquid ejectors 20. Eachchamber 30 includes a nozzle orifice 32 in nozzle plate 31 through whichliquid is ejected. A drop forming mechanism 34, for example, a resistiveheater, is also located in each chamber 30. In FIG. 2 a, the resistiveheater is positioned on the top surface of substrate 28 in the bottom ofchamber 30 and opposite nozzle orifice 32, although other configurationsare permitted. In other words, in this embodiment the bottom surface ofchamber 30 is the top of substrate 28, and the top surface of thechamber 30 is the nozzle plate 31.

A segmented liquid inlet or manifold 36 supplies liquid to each chamber30 through first and second liquid feed channels 38 and 40 that are influid communication with each chamber 30. Segmented inlet 36 includes afirst segment 37 that is in fluid communication with first liquid feedchannel 38 and a second segment 39 that is in fluid communication withsecond liquid feed channel 40. First segments 37 and second segments 39are positioned on opposite sides of chamber 30 and nozzle orifice 32.

In FIGS. 2 a and 2 b, each first segment 37 of liquid inlet 36 and eachsecond segment 39 of liquid inlet 36 are positioned offset relative toeach other as viewed from a plane perpendicular to a plane includingnozzle orifice 32 (the view shown in FIGS. 2 a and 2 b). Positioningfirst segment 37 and second segment 39 in this manner enables a segment(either first segment 37 or second segment 39) to provide liquid tochambers 30 that are aligned with the segment (represented by arrows 42)as well as provide liquid to chambers 30 that are offset from thesegment (represented by arrows 44). In FIG. 2 a, each of first segment37 and second segment 39 supply liquid to two chambers 30 that arealigned with or located across from each segment. Additionally, each offirst segment 37 and second segment 39 supply liquid to chambers 30 oneither side of each segment that are offset from or located adjacent toeach segment.

The flow patterns of FIG. 2 a are further clarified in FIG. 2 b, wheresome structural elements are omitted for simplification. Individualchambers 30 a, 30 b, 30 c and 30 d are designated, as are first segment37 a and second segments 39 a and 39 b of liquid inlet 36. In thedescription below, we will refer to a liquid feed channel feeding aparticular chamber. It should be understood that this means that thischannel primarily feeds the specified chamber (typically a nearbyneighbor channel). However, the channel also feeds other nearby channelsto a lesser extent, depending on flow requirements due to jet firingpatterns.

First liquid feed channel 38 a feeds chamber 30 a from second segment 39a of liquid inlet 36. In addition, second liquid feed channel 40 a alsofeeds chamber 30 a from first segment 37 a, which is offset from andadjacent to chamber 30 a. Both chambers 30 b and 30 c are fed by firstliquid feed channels 38 b and 38 c respectively from first segment 37 aof liquid inlet 36. Chamber 30 b is also fed by second liquid feedchannel 40 b from second segment 39 a, while chamber 30 c is also fed bysecond liquid feed channel 40 c from second segment 39 b. Chamber 30 dis fed by first liquid feed channel 38 d from second segment 39 b, andis also fed by second liquid feed channel 40 d from first segment 37 a.Each chamber is fed by a first liquid feed channel 38 from a segment ofliquid inlet 36 that is directly in line with the chamber, and also by asecond liquid feed channel 40 from a segment of liquid feed inlet 36that is offset somewhat from the chamber.

In FIGS. 2 a and 2 b, segments 37 and 39 of liquid inlet 36 are eachapproximately as wide as two adjacent chambers, and the spacing betweenadjacent segments 39 a and 39 b is also approximately as wide as twoadjacent chambers. In other words, two chambers are fed by first liquidfeed channels 38 from segments of liquid inlet 36 that are directly inline with the chambers, and the second feed channels 40 for these twochambers are from second segments that are offset somewhat from thechamber. Other configurations are possible. For example, FIG. 3 showsthe case of more than two chambers (i.e. 3, 4, or more chambers) beingfed by first liquid feed channels 38 from segments of liquid inlet 36that are directly in line with the chambers, and also by second liquidfeed channels 40 from segments of liquid inlet 36 that are somewhatoffset from the chambers.

Each of first segment 37 of the liquid inlet 36 includes ends 46 thatare adjacent to ends 48 of each second segment 39 of liquid inlet 38. InFIG. 2 a, an end 46 of first segment 37 is aligned with an end 48 ofsecond segment 39 represented by dashed line 50. However, otherconfigurations are permitted. For example, ends 46 and 48 can overlapeach other as is shown in FIG. 3. Alternatively, ends 46 and 48 can bepositioned spaced apart from each other as is shown in FIG. 4.

One or more posts 52 can be disposed in chamber 30, liquid feed channel38, liquid feed channel 40, or combinations thereof. As discussed inmore detail below, posts 52 can be symmetrically or asymmetricallydisposed about the nozzle orifice 32 and/or within one or both of liquidfeed channels 38, 40. Posts 52 can have the same cross sectional area ordifferent cross sectional areas when compared to each other. Posts 52can also have same shapes or different shapes when compared to eachother.

Referring to FIG. 5, a schematic cross sectional view of one liquidejector 20 is shown through line 5-5 of FIG. 4. Liquid ejector 20includes chamber 30 connected in fluid communication with first liquidfeed channel 38 which is connected in fluid communication to one of aplurality of first segments 37 of segmented liquid inlet or manifold 36.Chamber 30 is also connected in fluid communication with second liquidfeed channel 40 which is connected in fluid communication to one of aplurality of second segments 39 of segmented liquid inlet or manifold36. In FIG. 5, first segment 37 of liquid inlet 36 is aligned withchamber 30 and supplies liquid directly to chamber 30. Second segment 39of liquid inlet 36 is offset relative to chamber 30 and supplies liquidindirectly to chamber 30 (represented by “X” 54).

Drop forming mechanism 34, for example, a resistive heater, is locatedin chamber 30 and is operable to eject liquid through nozzle orifice 32.Posts 52 are also present in chamber 30 and/or one or both of first andsecond liquid feed channels 38 and 40.

Having described the basic components of the liquid ejector, we will nowreview the operation of the liquid ejector, as embodied in a thermalinkjet printhead, so that the advantages and reasons for thoseadvantages become more apparent. This discussion will also help toestablish the context for design variations described below.

Referring back to FIGS. 1-5, ink enters the printhead die throughsegmented liquid inlet 36 and passes through first and second liquidfeed channels 38 and 40 from opposite directions to enter the fluidchamber 30. In a conventional thermal inkjet printhead, the chamber isfilled with ink through a single liquid feed channel from only onedirection.

When the chamber is filled with ink, the resistive heating element 34,which is positioned below the nozzle orifice 32, is in thermal contactwith the pool of ink in the chamber. Resistive heating element 34 isshown in a particular configuration including two parallel legs 33 ofresistive material, joined at one end by a conductive shorting bar 35.Electrical leads 56 are connected to each leg 33 at the opposite endfrom the shorting bar 35. However, other resistive heating elementconfigurations are possible.

When data source 12 provides a signal that is interpreted by controller14 as a command for a drop of ink to be ejected from a particularchamber 30 at a particular time, source 16 provides an electrical pulseto heater 34 through electrical leads 56. The pulse voltage is chosensuch that a bubble is nucleated in the superheated ink over the heater.

As the bubble grows, it pushes the ink above it out through nozzleorifice 32, thus ejecting a drop. The size of the droplet (i.e. itsvolume or mass, and related to the size of the dot produced on recordingmedium 24) is determined primarily by size of the heater 34, size of thenozzle 32, and geometry of the chamber 30, and to a lesser extent on inktemperature and pulse configuration.

For accurate firing of jets, it is preferable for the droplet to beejected at a velocity of approximately 10 to 20 meters per second,depending somewhat on the size of the droplet. In order to increase thedrop velocity (and increase the energy efficiency, which is the energyof the drop divided by the energy input into the resistive heatingelement), it is helpful to preferentially direct the expansion of thebubble toward the nozzle. This is one of the functions of posts 52,which act as a source of lateral fluid impedance, so that a greateramount of the bubble expansion is directed toward the nozzle orifice 32.

Posts 52 also restrict the amount and momentum of liquid flow away fromchamber 30, so that the refill of the chamber 30 is able to occur morequickly. Refill of chamber 30 is typically the rate limiting step forhow quickly the same chamber can be fired again. After the drop isejected, liquid feeds in from inlet 36 through liquid feed channels 38and 40 and into the chamber. The dual feed configuration of theinvention increases refill rate (and hence printing throughput speeds)for several reasons. As mentioned above, posts 52 restrict the backflowof ink so that the reversal of ink flow can happen more quickly. Anotherimportant factor promoting faster refill is the existence of two feedchannels 38 and 40 rather than a single feed channel, thereby increasingthe rate of flow of ink back into the chamber. In addition, compared toconventional liquid ejectors, which are fed from one side of thechamber, but have a fluidic dead-end at the opposite side of thechamber, the liquid ejector 20 described herein is fed from two oppositesides of the chamber. As a result, the ink-air interface possessessymmetric curvature relative to the chamber during refill, whichenhances the pressure differences that drive refill, so that refilloccurs more rapidly. Computer simulations of flow for the dual feedconfiguration indicate that refill rate is approximately twice as highas for a comparable single feed configuration.

As can be seen in FIGS. 2 a and 2 b, first segment 37 of segmented inlet36 feeds liquid feed channel 38 which is directly in front of firstsegment 37. Second segment 39 feeds liquid feed channel 40 which isoffset from second segment 39. Due to the different fluid path lengths,there is a difference between fluid impedances from segment 37 and feedchannel 38 to chamber 30, as compared with the fluid impedance fromsegment 39 and fluid channel 40. Therefore, in some embodiments theposition or cross-sectional area of one or more posts may be modified tocompensate for this difference in fluid impedance. For example, in FIG.6, post 52 b in feed channel 40 is moved further away from nozzleorifice 32 than post 52 a is in feed channel 38. Similarly, in FIG. 7,post 52 b in feed channel 40 is formed with a smaller cross-sectionalarea than post 52 a in feed channel 38. FIGS. 6 and 7 show all posts 52a in feed channels 38 being located similarly to one another and with afirst same cross-sectional area, and similarly all posts 52 b in feedchannels 40 being located similarly to one another and with a secondsame cross-sectional area. However, it may be understood, particularlyfor liquid inlet 36 configurations similar to that shown in FIG. 3,where more than 2 chambers are somewhat offset from the correspondingsegment, that it may be advantageous for some posts 52 b in feedchannels 40 to be sized or positioned differently from other posts 52 bin other feed channels 40, for example. A different cross-sectionalshape is permitted. In other embodiments, the posts 52 may besymmetrically positioned about the nozzle orifice and may have the samecross-sectional area as each other (as shown in FIGS. 2 a and 2 b).

A lower magnification top view of a portion of liquid ejection printheaddie 18 is shown in FIG. 8. The twenty-four chambers shown in FIG. 8 arefed by a liquid inlet 36 consisting of six segments 37 on one side ofthe chambers and six segments 39, which are offset from segments 37, onthe other side of the chambers. A typical liquid ejection printhead diewould typically have hundreds or even thousands of chambers andcorresponding segments 37 and 39 of liquid feed inlet 36. FIG. 8contains other elements similar to FIG. 2 a, including walls 26, nozzleorifices 32, resistive heating elements 34, electrical leads 56, andposts 52. In addition, FIG. 8 shows optional filter posts 41 locatedbetween segments 37, 39 of liquid inlet 36 and the nozzle orifices 32,i.e. within the respective liquid feed channels 38 and 40. Filter posts41 block particulates from clogging the chamber at post 52 or nozzle 32.Even if a particle is caught between two adjacent filter posts, thereare many parallel redundant fluid paths around the line of filter posts,so that all chambers would continue to be supplied with ink.

As shown in FIG. 8, liquid inlet 36 may be formed through substrate 28such that first segments 37 and second segments 39 are relatively closeto nozzle orifices 32. However, it is necessary to bring electricalleads toward an edge 58 of the printhead die, such as edge 58 a or 58 bshown in FIG. 1. Typically one or more rows of bond pads (not shown) areprovided along one or more edges 58, so that electrical interconnectionmay be made from liquid ejection printhead die 18 and electrical pulsesource 16. As shown in FIG. 8, at least one electrical lead 56 extendsfrom each drop forming mechanism 34 toward an edge 58 of printhead die18. Further, at least one of the electrical leads 56 is positionedbetween either neighboring segments of first segments 37 or secondsegments 39. In FIG. 8, some electrical leads 56 are positioned betweenneighboring first segments 37, while other electrical leads 56 arepositioned between neighboring second segments 39 of liquid inlet 36.

Offsetting first and second segments 37 and 39 provides more room toposition the electrical leads while still providing sufficient liquidrefill of chamber 30. Accordingly, it is possible to locate eachelectrical lead 56 such that none of the electrical leads 56 extendtoward first segments 37 as shown in FIG. 9. Alternatively it ispossible to locate each electrical lead 56 such that none of theelectrical leads 56 extend toward second segments 39 (not shown). Atleast one of electrical leads 56 can be positioned between neighboringsegments 37 and/or 39 as is shown in FIG. 9.

Each resistive heating element 34 is connected to two electrical leads56 a and 56 b. Leads 56 a may, for example, be ultimately connected to aconstant voltage, while leads 56 b may, for example, be connected toindividual switches which are addressed by electrical pulse source 16,and optionally controlled by logic circuitry on liquid ejectionprinthead die 18. In order to reduce the number of leads which need tobe positioned between neighboring segments 39 in the embodimentillustrated in FIG. 9, each of the leads 56 a are connected by vias 57to common lead 59 which runs parallel to the segments 39, rather thanpassing between adjacent segments 39 of liquid inlet 36. Via 57 islocated between nozzle orifice 32 and inlet segments 39. Common lead 59is typically formed on a different metal layer than leads 56 b, andcommon lead 59 is electrically insulated from leads 56 b where itcrosses over them. Common lead 59 may extend all the way to theprinthead die edge 58 which is at the end of the array of nozzleorifices 32 without going between adjacent segments 39. Alternatively,as shown in FIG. 10, several leads 56 a may be connected at vias 57 to acommon lead 59 which passes between adjacent segments 39. In theembodiment shown in FIG. 9, four leads 56 b pass between adjacentsegments 39, while in the embodiment shown in FIG. 10, four leads 56 bplus common lead 59 pass between adjacent segments 39.

FIG. 11 schematically illustrates a liquid ejector printhead die 18 inwhich power circuitry and logic circuitry are integrated together on thesame substrate 28 as the liquid ejectors 20. The power circuitry isillustrated as an array of driver transistors 60 which function asswitches to allow the resistive heating elements 34 to be activated. Forsimplicity in FIG. 11, the resistive heating elements (located beloworifices 32) are not shown, but it is to be understood that theelectrical leads 56 b extend from the driver transistors to therespective resistive heating elements 34, and not to the orifices 32.The driver transistors 60 are controlled by logic circuitry 62integrated on liquid ejector printhead die 18, in order to minimize thenumber of electrical interconnections (for example at printhead die edge58 a) made to electrical circuitry such as pulse source 16 andcontroller 14. Logic circuitry 62 typically includes circuit elementssuch as shift registers, so that data may be shifted serially intoliquid ejector printhead die 18, rather than requiring separateinterconnections to printhead die 18 for each transistor. Voltage 64 isconnected to common leads 59, which are not individually shown, but arerepresented by the dashed line.

In the embodiment shown in FIG. 11, only two leads 56 b are shownpassing between adjacent segments 39 of liquid inlet 36. This may beunderstood as representing all of the leads 56 b which pass betweenadjacent segments 39 to driver transistors 60. Driver transistors 60 arelocated on the side of segments 39 which is opposite the nozzle orificeside of segment 39. However, the drivers may instead be located nearfirst segments 37 rather than near second segments 39. Logic circuitry62 will typically be located on the side of driver transistors 60 whichis opposite from the nozzle orifice side of driver transistors 60.

FIG. 12 schematically illustrates a liquid ejector printhead die 18having two rows of liquid ejectors 20 a and 20 b forming a twodimensional array of chambers and orifices. In this embodiment,segmented liquid inlet 36 is composed of three rows of segments. Acentral row of segments 66 is positioned between the two rows of liquidejectors 20 a and 20 b, and feeds liquid ejectors in both rows. Inaddition, two outer rows of segments 68 a and 68 b are positioned on theopposite sides of liquid ejectors 20 a and 20 b respectively, relativeto central row of segments 66. Driver transistors 60 and logic circuitry62 are also shown corresponding to both rows of liquid ejectors 20 a and20 b. At least one electrical lead 56 b is positioned betweenneighboring segments 68 a (and similarly for neighboring segments 68 b)in order to provide electrical connection between ejector 20 andcorresponding driver transistor 60. Inlet segments 68 a are positionedbetween ejectors 20 a and corresponding driver transistors 60.Similarly, inlet segments 68 b are positioned between ejectors 20 b andcorresponding driver transistors 60. Such a configuration of segmentedliquid inlet 36 enables a higher density of liquid ejectors 20 to beprovided, where each of the liquid ejectors is fed from two segments intwo different directions (analogous to the previous dual-fed embodimentsfor only a single row of liquid ejectors 20).

FIGS. 12 and 13 illustrate one embodiment of a two dimensional array ofdual fed liquid ejectors. Here the nozzle orifices 32 corresponding toliquid ejectors 20 a are offset by half a nozzle spacing from the nozzleorifices 32 corresponding to liquid ejectors 20 b (as seen by nozzleposition relative to the dashed line). As a result of the two staggeredrows, such a liquid ejection printhead die 18 has twice the effectiveprinting resolution as a printhead die with a single row of liquidejectors 20. For example, if rows of liquid ejectors 20 a and 20 b areeach at spacings of 600 nozzles per inch, the composite printingresolution would be 1200 spots per inch.

FIG. 14 illustrates a second embodiment of a two-dimensional array ofdual fed liquid ejectors. Here the nozzle orifices 32 corresponding toliquid ejectors 20 a are in line with nozzle orifices 32 correspondingto liquid ejectors 20 b. This configuration provides redundant nozzlesat each pixel location, so that if one drop ejector 20 a fails, thecorresponding drop ejector 20 a may still be used to print a pixel. Rowsof aligned nozzles can also be used to increase the printing frequency.

In FIGS. 13 and 14, segments 66 in the central row of liquid inlet 36are shown as having a larger cross-sectional area than segments 68 inthe outer rows of liquid inlet 36. This helps to provide the requiredfluid flow for feeding both liquid drop ejectors 20 a and 20 b on eitherside of central row 66.

For either the case of staggered rows or aligned rows of liquid ejectors20, it is also possible to configure chambers 30, heaters 34, andnozzles 32 such that different sized drops are ejected from liquidejectors 20 b relative to 20 a. For example, the nozzle orificescorresponding to the different drop sizes would have differentcross-sectional areas. FIG. 18 illustrates an embodiment where two rowsof liquid ejectors 20 are staggered, and where nozzle orifices 32 a ofliquid ejectors 20 a have a smaller cross-sectional area than nozzleorifices 32 b of liquid ejectors 20 b. The two different sized dropswould provide a level of gray scale printing.

For the embodiments discussed in detail up to this point, the number ofsegments in segmented inlet 36 has been configured to be fewer than thetotal number of liquid ejectors 20. For many sizes of inlet segments andspacings of liquid ejectors, providing approximately twice as manyliquid ejectors as inlet segments provides an adequate balance betweenthe requirements of providing improved liquid flow to the ejector forfaster refill and printing throughput, and routing all electrical leads56 from the ejector region toward an edge 58 of the printhead die 18.However, for configurations in which the inlet segments can be madesmall enough relative to the ejector spacing and the width and spacingof electrical leads 56, it may be advantageous to have more than oneinlet segment for every two liquid ejectors 20.

For example in the two embodiments illustrated in FIGS. 15 and 16, thereare three segments 37 and three segments 39 of liquid inlet 36, andthere are 6 ejectors 20. In other words, for this limited view of theprinthead die 18 (and by extension for the entire printhead die 18) thetotal number of segments of liquid inlet 36 is the same as the number ofliquid ejectors 20. Although the electrical leads are not shown in FIGS.15 and 16, it is clear that the leads could be routed between adjacentsegments 39 and/or between adjacent segments 37. In FIGS. 15 and 16 itis also clear that each segment feeds the ejector directly in line withit, as well as the neighboring ejector. In FIG. 15 the segments 37 areoffset relative to the segments 39, so that one ejector is directly inline with a segment 39, while the adjacent ejector is directly in linewith a segment 37. In FIG. 16, the segments 37 are directly in line withthe segments 39, so that one ejector is directly in line with a segment37 and a segment 39, but the adjacent ejector is offset from itsneighboring segments 37 and 39. Lastly, FIG. 17 illustrates anembodiment where there are two inlet segments (one each 37 and 39) foreach ejector 20. The inlet segments 37 and 39 are shown as beingdirectly in line with ejectors 20. Such a configuration may beadvantageous in situations where the ejector spacing is large enoughrelative to the manufacturable sizes of inlet segments 37 and 39, aswell as to the width and spacing of electrical leads 56.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the scope of theinvention.

PARTS LIST

-   -   10 liquid ejection system    -   12 data source    -   14 controller    -   16 electrical pulse source    -   18 liquid ejection printhead die    -   20 liquid ejector    -   24 recording medium    -   26 wall    -   28 substrate    -   30 chamber    -   31 nozzle plate    -   32 nozzle orifice    -   33 resistive material    -   34 resistive heating element    -   35 conductive shorting bar    -   36 segmented liquid inlet    -   37 first segment    -   38 first liquid feed channel    -   39 second segment    -   40 second liquid feed channel    -   41 filter post    -   42 liquid flow arrows    -   44 liquid flow arrows    -   46 first segment end    -   48 second segment end    -   50 line relative to first and second segment ends    -   52 post    -   54 indirect liquid supply X    -   56 electrical lead    -   57 via    -   58 printhead die edge    -   59 common lead    -   60 driver transistors    -   62 logic circuitry    -   64 voltage    -   66 segment in central row    -   68 segment in outer row

1. A liquid ejector comprising: a structure defining a plurality ofchambers, one of the plurality of chambers including a first surface anda second surface, the first surface including a nozzle orifice; a dropforming mechanism located on the second surface of the chamber oppositethe nozzle orifice; a first liquid feed channel and a second liquid feedchannel being in fluid communication with the chamber; and a segmentedliquid inlet, a first segment of the liquid inlet being in fluidcommunication with the first liquid feed channel, and a second segmentof the liquid inlet being in fluid communication with the second liquidfeed channel, the first segment of the liquid inlet also being in fluidcommunication with another one of the plurality of chambers, the secondsegment of the liquid inlet also being in fluid communication withanother one of the plurality of chambers.
 2. The liquid ejectoraccording to claim 1, wherein the first segment of the liquid inlet andthe second segment of the liquid inlet are positioned offset relative toeach other as viewed from a plane perpendicular to the nozzle orifice.3. The liquid ejector according to claim 2, the first segment of theliquid inlet having an end adjacent to an end of the second segment ofthe liquid inlet, wherein the end of the first segment overlaps the endof the second segment.
 4. The liquid ejector according to claim 2, thefirst segment of the liquid inlet having an end adjacent to an end ofthe second segment of the liquid inlet, wherein the end of the firstsegment is aligned with the end of the second segment.
 5. The liquidejector according to claim 2, the first segment of the liquid inlethaving an end adjacent to an end of the second segment of the liquidinlet, wherein the end of the first segment is spaced apart from the endof the second segment.
 6. The liquid ejector according to claim 1,further comprising a post disposed in at least one of the first andsecond liquid feed channels.
 7. The liquid ejector according to claim 1,further comprising a post disposed in each of the first and secondliquid feed channels.
 8. The liquid ejector according to claim 7,wherein the posts are symmetrically disposed about the nozzle orifice.9. The liquid ejector according to claim 7, wherein the posts have thesame cross sectional area.
 10. The liquid ejector according to claim 7,wherein the posts are non-symmetrically disposed about the nozzleorifice.
 11. The liquid ejector according to claim 7, wherein the postshave different cross sectional areas.
 12. The liquid ejector accordingto claim 7, further comprising at least one additional post disposed inat least one of the first liquid feed channel and the second liquid feedchannel between the nozzle orifice and at least one of the first segmentof the liquid inlet and the second segment of the liquid inlet.
 13. Theliquid ejector according to claim 1, wherein the first and second feedchannels extend in opposite directions from the chamber.
 14. The liquidejector according to claim 1, wherein the first segment and the secondsegment of the liquid inlet are located on opposite sides of the nozzleorifice.
 15. The liquid ejector according to claim 1, wherein theanother one of the plurality of chambers that is in fluid communicationwith the first segment of the liquid inlet is the same chamber as theanother one of the plurality of chambers that is in fluid communicationwith the second segment of the liquid inlet.
 16. The liquid ejectoraccording to claim 1, wherein for a given chamber of the plurality ofchambers one of the first segment of the liquid inlet and the secondsegment of the liquid inlet is directly in line with the chamber and theother of the first segment of the liquid inlet and the second segment ofthe liquid inlet is offset from the chamber.
 17. A liquid ejectorcomprising: a structure defining an array of chambers, each chamberhaving a nozzle orifice; a drop forming mechanism located in eachchamber; first and second liquid feed channels being in fluidcommunication with each chamber, the first and second feed channelsextending in opposite directions from each chamber; and a segmentedinlet comprising a plurality of first segments and a plurality of secondsegments, each of the first segments of the liquid inlet being in fluidcommunication with the first liquid feed channels, and each of thesecond segments of the liquid inlet being in fluid communication withthe second liquid feed channels, wherein the plurality of first segmentsand the plurality of second segments are located on opposite sides ofthe nozzle orifice, and wherein for a given chamber of the array ofchambers one of the first segment of the liquid inlet and the secondsegment of the liquid inlet is directly in line with the chamber and theother of the first segment of the liquid inlet and the second segment ofthe liquid inlet is offset from the chamber.
 18. The liquid ejectoraccording to claim 17, further comprising an electrical lead extendingfrom each drop forming mechanism toward an edge of the structure,wherein at least one of the electrical leads is positioned betweenneighboring segments of at least one of the plurality of first segmentsand the plurality of second segments of the liquid inlet.
 19. The liquidejector according to claim 18, further comprising power circuitryincluding a plurality of drivers, each driver being in electricalcommunication with a corresponding drop forming mechanism through acorresponding electrical lead.
 20. The liquid ejector according to claim17, further comprising an electrical lead extending from each dropforming mechanism toward an edge of the structure, wherein none of theelectrical leads extend toward the plurality of second segments of theliquid inlet.
 21. The liquid ejector according to claim 20, wherein atleast one of the electrical leads is positioned between neighboringsegments of the plurality of first segments of the liquid inlet.
 22. Theliquid ejector according to claim 20, further comprising power circuitryincluding a plurality of drivers, each driver being in electricalcommunication with a corresponding drop forming mechanism through acorresponding electrical lead, wherein each driver is located on a sideof the plurality of first segments of the liquid inlet which is oppositea nozzle orifice side of the plurality of first segments of the liquidinlet.
 23. The liquid ejector according to claim 17, further comprisingan electrical lead extending from each drop forming mechanism toward anedge of the structure, one electrical lead from one of the drop formingmechanisms being electrically connected to another electrical lead fromanother of the drop forming mechanisms at a location between the nozzleorifice and the segmented inlet.
 24. The liquid ejector according toclaim 23, the one electrical lead from one of the drop formingmechanisms that is electrically connected to another electrical leadfrom another of the drop forming mechanisms being a combined electricallead, the combined electrical lead extending toward the edge of thestructure between neighboring segments of at least one of the pluralityof first segments and the plurality of second segments of the liquidinlet.
 25. The liquid ejector according to claim 17, wherein the arrayof chambers is a two dimensional array of chambers, each chamber havinga nozzle orifice such that a two dimensional array of nozzle orifices ispresent.
 26. The liquid ejector according to claim 25, wherein thenozzle orifices of the two dimensional array of nozzle orifices arestaggered relative to each other.
 27. The liquid ejector according toclaim 25, the segmented inlet further comprising a plurality of thirdsegments, each of the third segments of the liquid inlet beingpositioned between the nozzle orifices of the two dimensional array ofnozzle orifices.
 28. The liquid ejector according to claim 27, whereinthe nozzle orifices of the two dimensional array of nozzle orifices arestaggered relative to each other.
 29. The liquid ejector according toclaim 28, further comprising an electrical lead extending from each dropforming mechanism toward an edge of the structure, wherein at least oneof the electrical leads is positioned between neighboring segments of atleast one of the plurality of first segments and the plurality of secondsegments of the liquid inlet.
 30. The liquid ejector according to claim29, further comprising power circuitry including a plurality of drivers,each driver being in electrical communication with a corresponding dropforming mechanism through a corresponding electrical lead.
 31. Theliquid ejector according to claim 30, wherein each driver is located ona side of the plurality of first segments or the plurality of secondsegments of the liquid inlet which is opposite a nozzle orifice side ofthe plurality of first segments or the plurality of second segments ofthe liquid inlet.
 32. The liquid ejector according to claim 27, whereinthe nozzle orifices of the two dimensional array of nozzle orifices arealigned relative to each other.
 33. The liquid ejector according toclaim 27, each of the plurality of third segments of the liquid inlethaving a cross sectional area that is larger than a cross sectional areaof each of the plurality of first segments and each of the plurality ofsecond segments, the cross sectional area being viewed from a planeperpendicular to the nozzle orifices.
 34. The liquid ejector accordingto claim 25, the nozzle orifices of one portion of the two dimensionalnozzle orifice array have a cross sectional area that is different froma cross sectional area of nozzle orifices of another portion of the twodimensional nozzle orifice array, the cross sectional area being viewedfrom a plane perpendicular to the nozzle orifices.
 35. The liquidejector according to claim 17, wherein each of the plurality of firstsegments of the liquid inlet are positioned offset relative to each ofthe plurality of second segments of the liquid inlet.
 36. The liquidejector according to claim 17, wherein each of the plurality of firstsegments of the liquid inlet are positioned aligned relative to each ofthe plurality of second segments of the liquid inlet.
 37. The liquidejector according to claim 17, wherein the liquid ejector satisfies thefollowing condition: N<2 (M₁+M₂), where N is the total number ofchambers, M₁ is the total number of first segments, and M₂ is the totalnumber of second segments.
 38. A liquid ejector comprising: a structuredefining an array of chambers, each chamber having a nozzle orifice; adrop forming mechanism located in each chamber; first and second liquidfeed channels being in fluid communication with each chamber, the firstand second feed channels extending in opposite directions from eachchamber; and a segmented inlet comprising a plurality of first segmentsand a plurality of second segments, each of the first segments of theliquid inlet being in fluid communication with the first liquid feedchannels, and each of the second segments of the liquid inlet being influid communication with the second liquid feed channels, wherein theplurality of first segments and the plurality of second segments arelocated on opposite sides of the nozzle orifice, wherein the liquidejector satisfies the following condition: N≧2(M₁+M₂), where N is thetotal number of chambers, M₁ is the total number of first segments, andM₂ is the total number of second segments.
 39. A liquid ejectorcomprising: a structure defining a plurality of chambers, each of thechambers having a nozzle orifice; a drop forming mechanism located ineach chamber; first and second liquid feed channels being in fluidcommunication with each chamber; and a segmented inlet, a first segmentof the liquid inlet being in fluid communication with the first liquidfeed channel in fluid communication with one of the chambers, and asecond segment of the liquid inlet being in fluid communication with thesecond liquid feed channel in fluid communication with one of thechambers, the first segment of the liquid inlet and the second segmentof the liquid inlet being positioned offset relative to each other asviewed from a plane perpendicular to the nozzle orifice such that for agiven chamber of the plurality of chambers one of the first segment ofthe liquid inlet and the second segment of the liquid inlet is directlyin line with the chamber and the other of the first segment of theliquid inlet and the second segment of the liquid inlet is offset fromthe chamber, the first segment of the liquid inlet also being in fluidcommunication with another one of the plurality of chambers, the secondsegment of the liquid inlet also being in fluid communication withanother one of the plurality of chambers.